Polymeric fluorescent substance and organic electroluminescence device

ABSTRACT

Disclosed are an organic electroluminescence device having at least a light emitting layer between the electrodes consisting of one pair of an anode and a cathode, at least one of which electrodes is transparent or semi-transparent, wherein said light emitting layer comprises a polymeric fluorescent substance which emits a fluorescence in a solid state, is soluble in solvents and comprises at least one kind of repeating unit represented by the following formula (1) and at last one kind of repeating unit represented by the following formula (2) with the number of the formula (1) repeating units being 2-50% of the total number of all the repeating units:-Ar1-(1)-Ar2-(2)wherein Ar1 and Ar2 are each a bifunctional group forming a carbon-carbon bond with each of two adjacent groups, in the chemical structure of Ar1, the number of the consecutive atoms present in the shortest path between the two carbon atoms bonding to said two adjacent groups is 1, 3 or 5, and in the chemical structure of Ar2, the total number of the carbon and nitrogen atoms present in the shortest path between the two carbon atoms bonding to said two adjacent groups is an even number, and a novel polymeric fluorescent substance used in the above device.

This is a divisional of application Ser. No. 08/397,489 filed Mar. 2,1995, now U.S. Pat. No. 5,759,709.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to organic electroluminescence devices(which may hereinafter referred to as organic EL devices) and polymericfluorescent substances used therein. More particularly, the presentinvention relates to organic EL devices with high luminous efficiencyand polymeric fluorescent substances used therein, having a strongfluorescence and being soluble in solvents.

2. Description of the Related Art

Inorganic electroluminescence devices (which may hereinafter be referredto as inorganic EL devices) using an inorganic fluorescent substance asthe light emitting material have been applied to various uses, forexample, as a flat light source for backlight of liquid crystal displaysand various display devices such as flat panel display and the like. Inthese devices, however, a high-voltage alternating current has beenrequired for driving the devices.

Recently, Tang et al. manufactured an organic EL device having adouble-layer structure comprising a laminate of a light emitting layermade of an organic fluorescent dye and a layer of an organic chargetransport compound generally used, for example, in a photosensitivelayer for electrophotography to realize a low-voltage-drive,high-efficiency and high-luminance organic EL device (JP-A-59-194393).In view of many advantageous features of organic EL devices as comparedwith inorganic EL devices, such as low-voltage drive, high luminance andeasy luminescence of a large number of colors, various attempts havebeen made and reported regarding the development and improvement of thedevice structure, organic fluorescent dye and organic charge transportcompound used in organic EL devices [Jpn. J. Appl. Phys., Vol. 27, L269(1988); J. Appl. Phys., Vol. 65, p. 3610 (1989)].

Hitherto, low-molecular weight organic fluorescent dyes have generallybeen used as a material of the light emitting layer and, regardingpolymeric light emitting materials, proposals have been made in somepatents and publications such as WO9013148, JP-A-3-244630 and-Appl.Phys. Lett., Vol. 58, p. 1982 (1991). WO9013148 discloses in theExamples an EL device using a thin film of poly(p-phenylene vinylene)obtained by forming a film of a soluble precursor on the electrode andsubjecting it to a heat treatment to convert the precursor into aconjugated polymer.

JP-A-3-244630 illustrates conjugated polymers having a salient featurethat they are themselves soluble in solvents and make heat treatmentunnecessary. In Appl. Phys. Lett., Vol. 58, 1982 (1991) are alsodisclosed polymeric light emitting materials soluble in solvents andorganic EL devices made by using such materials. Most of the organic ELdevices manufactured by using these materials, however, were notsufficiently high in luminous efficiency.

An attempt to increase the quantum yield of fluorescence of polymericlight emitting material is already reported in Nature, Vol. 356, p. 47(1992). In the literature, it is described that by, in the course offorming a conjugated segment from a soluble precursor copolymer by heattreating, allowing the non-conjugated segment of the copolymer to remainunchanged, there can be obtained a polymer having both a conjugatedsegment and a non-conjugated segment and emitting a strong fluorescence.Here, since the 2,5-dimethoxy-p-phenylene-methoxy-ethylene moiety in thecopolymer is hard to decompose by heat treatment alone, it is utilizedfor inhibiting the copolymer from being converted in its entirety into aconjugated polymer by the heat treatment.

It is further reported that a polymer in which a conjugated monomericmoiety with strong fluorescence and an aliphatic hydrocarbon are coupledvia an ether linkage, generates a blue fluorescence because of its shortconjugated chain length, and a blue light-emitting organic EL device canbe made by using said polymer [Macromolecules, Vol. 26. p. 1188 (1993)].

It is also reported that an alternating copolymer composed ofunsubstituted p-phenylene vinylene and unsubstituted m-phenylenevinylene has a greenish blue fluorescence [Vysokomolekul. Soedin., Vol.5, p. 805 (1963)]. However, the quantum yield of fluorescence and ELproperties of said copolymer are unknown.

With respect to the luminous efficiency of organic EL device, it isreported that since a poly-p-phenylene vinylene derivative (in which acyano group is introduced into the vinylene group of p-phenylenevinylene) having a red fluorescence has high electron affinity andenables easy electron injection thereinto, said derivative allows forthe production of an organic EL device which is high in luminousefficiency, i.e. the proportion of photons released per one electroninjected [Nature, Vol. 365, p. 628 (1993)].

However, in the manufacture of organic EL devices using polymersreported hitherto, it has been necessary to mold a soluble precursorinto a thin film and convert its structure into a conjugated polymericstructure by high-temperature heat treatment, so that there have beenrestrictions on the materials used for the associated parts such assubstrate and the like in said manufacture. Also, when a precursorpolymer is converted into a conjugated polymer by heat treatment,control of the non-conjugated moiety in the latter polymer has been madeby adjusting the heat treatment conditions, so that such control has notbeen perfect and, when the conjugated polymer was used for an organic ELdevice, the device had, in long-time continuous drive, a fear of changein the structure owing to the heat generation of the device or otherfactors.

When there is used a polymer in which a conjugated monomeric moiety iscoupled with a non-conjugated aliphatic hydrocarbon via an etherlinkage, the polymer has a short conjugated chain (the length ofconjugated chain is thought to contribute to transport of charge) andthereby the transfer of charge in the polymer is feared to be difficult.

In the case of soluble conjugated polymers, although no high-temperatureheat treatment is necessary after formation of the resin film, furtherimprovements are required on the quantum yield of fluorescence as wellas on the luminous efficiency of the EL devices using said polymers.

As to the hitherto known poly-p-phenylene vinylene derivatives in whicha cyano group is introduced into the vinylene group of the p-phenylenevinylene, no detail is disclosed on the quantum yield of fluorescence ofsaid polymers.

Thus, there have been desired a polymeric fluorescent substance whichhas excellent solvent solubility, high quantum yield of fluorescence andexcellent electrical conductivity; and an organic EL device of highluminance which can easily be produced using said polymeric fluorescentsubstance by coating.

The objects of the present invention are to provide a polymericfluorescent substance having high quantum yield of fluorescence,excellent solvent solubility and excellent charge transport; and anorganic EL device of high luminance and high luminous efficiency whichcan easily be produced using said polymeric fluorescent substance bycoating.

SUMMARY OF THE INVENTION

In view of the above situation, the present inventors made a study onthe improvement of the luminous efficiency of the organic EL deviceusing a polymeric fluorescent substance for the light emitting layer. Asa result, the present inventors found out that a polymeric fluorescentsubstance containing, in the main chain, repeating units of particularstructure each having conjugated bond(s) has a high quantum yield offluorescence and that an organic EL device of high luminous efficiencycan easily be produced using said polymeric fluorescent substance bycoating. The finding has led to the completion of the present invention.

The present invention includes the followings.

(1) An organic electroluminescence device having at least a lightemitting layer between the electrodes consisting of one pair of an anodeand a cathode, at least one of which electrodes is transparent orsemi-transparent, wherein said light emitting layer comprises apolymeric fluorescent substance which emits a fluorescence in a solidstate, is soluble in solvents and comprises at least one kind ofrepeating unit represented by the following formula (1) and at least onekind of repeating unit represented by the following formula (2) with thenumber of the formula (1) repeating units-being 2-50% of the totalnumber of all the repeating units:

    --Ar.sub.1 --                                              (1)

wherein Ar₁ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent groups and is selected from the group consisting ofan aromatic compound group having 6-22 carbon atoms taking part in theconjugated bonds, an at least 6-membered heterocyclic aromaticcompound-group having at least one hetero atom and 4-20 carbon atoms,and a group composed of said aromatic compound group or saidheterocyclic aromatic compound group and a vinylene group; in thechemical structure of Ar₁, the number of the consecutive atoms presentin the shortest path between the two carbon atoms bonding to said twoadjacent groups is 1, 3 or 5, and

    --Ar.sub.2 --                                              (2)

wherein Ar₂ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent groups and is selected from the group consisting ofan aromatic compound group having 6-22 carbon atoms taking part in theconjugated bonds, an at least 5-membered heterocyclic aromatic compoundgroup having at least one hetero atom and 4-20 carbon atoms, and a groupcomposed of said aromatic compound group or said heterocyclic aromaticcompound group and a vinylene group; in the chemical structure of Ar₂,the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said two adjacentgroups is an even number.

(2) An organic electroluminescence device according to (1), wherein therepeating unit of formula (1) and the repeating unit of formula (2),both of the solvent-soluble polymeric fluorescent substance are arepeating unit of the following formula (3) and a repeating unit of thefollowing formula (4), respectively:

    --Ar.sub.3 --CR.sub.1 ═CR.sub.2 --                     (3)

    --Ar.sub.4 --CR.sub.3 ═CR.sub.4 --                     (4)

wherein Ar₃ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-20 carbon atoms takingpart in the conjugated bonds and an at least 6-membered heterocyclicaromatic compound group having at least one hetero atom and 4-18 carbonatoms; in the chemical structure of Ar₃, the number of the consecutiveatoms present in the shortest path between the two carbon atoms bondingto said two adjacent vinylene groups is 1, 3 or 5; Ar₄ is a bifunctionalgroup forming a carbon--carbon bond with each of two adjacent vinylenegroups and is selected from the group consisting of an aromatic compoundgroup having 6-20 carbon atoms taking part in the conjugated bonds andan at least 5-membered heterocyclic aromatic compound group having atleast one hetero atom and 4-18 carbon atoms; in the chemical structureof Ar₄, the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said two adjacentvinylene groups is an even number; and R₁, R₂, R₃ and R₄ areindependently is a group selected from the group consisting of ahydrogen atom, a cyano group, an alkyl group of 1-20 carbon atoms and anaryl group of 6-18 carbon atoms.

(3) An organic electroluminescence device according to (1) or (2),wherein the repeating unit of formula (1) or the Ar₃ portion of formula(3) is selected from repeating units each containing at least one of thestructures represented by the following formula (5): ##STR1## wherein R₅to R₃₇ are independently a group selected from the group consisting of ahydrogen atom, a cyano group, an alkyl, alkoxy or alkylthio group of1-20 carbon atoms, an aryl or aryloxy-group of 6-18 carbon atoms and aheterocyclic compound group of 4-14 carbon atoms.

(4) An organic electroluminescence device according to (1), (2) or (3),wherein the polymeric fluorescent substance is a copolymer comprisingrepeating units represented by the following formulas (6) and (7):##STR2## wherein X₁ is a group selected from the group consisting ofC--R₄₉ and N; R₃₈ to R₄₁, R₄₄ to R₄₆ and R₄₉ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms and a heterocyclic aromatic group of4-14 carbon atoms; and R₄₂, R₄₃, R₄₇ and R₄₈ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl group of 1-20 carbon atoms and an aryl group of 6-18 carbon atoms.

(5) An organic electroluminescence device according to (1), (2), (3) or(4), wherein the polymeric fluorescent substance is a polymericfluorescent substance comprising at least one repeating unit selectedfrom the repeating units represented by the following formula (8):##STR3## wherein Ar₅, Ar₈ and Ar₉ are each a bifunctional group forminga carbon--carbon bond with each of two adjacent vinylene groups and isselected from the group consisting of an aromatic compound group having6-20 carbon atoms taking part in the conjugated bonds and an at least5-membered heterocyclic aromatic compound group having at least onehetero atom and 4-18 carbon atoms; in the chemical structure of each ofAr₅, Ar₈ and Ar₉, the total number of the consecutive carbon andnitrogen atoms present in the shortest path between the two carbon atomsbonding to said two adjacent vinylene groups is an even number; Ar₆ andAr₇ are each a bifunctional group forming a carbon--carbon bond witheach of two adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-20 carbon atoms takingpart in the conjugated bonds and an at least 6-membered heterocyclicaromatic compound group having at least one hetero atom and 4-18 carbonatoms; in the chemical structure of each of Ar₆ and Ar₇, the number ofthe consecutive atoms present in the shortest path between the twocarbon atoms bonding to said two adjacent vinylene groups is 1, 3 or 5.

(6) An organic electroluminescence device according to (1), (2), (3),(4) or (5), wherein a layer comprising an electron transport compound isprovided between the cathode and the light emitting layer in adjacencyto the light emitting layer.

(7) An organic electroluminescence device according to (1), (2), (3),(4) or (5), wherein a layer comprising a hole transport compound isprovided between the anode and the light emitting layer in adjacency tothe light emitting layer.

(8) An organic electroluminescence device according to (1), (2), (3),(4) or (5), wherein a layer comprising an electron transport compound isprovided between the cathode and the light emitting layer in adjacencyto the light emitting layer and a layer comprising a hole transportcompound is provided between the anode and the light emitting layer inadjacency to the light emitting layer.

(9) A polymeric fluorescent substance which is soluble in solvents,emits a fluorescence in a solid state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and comprises a repeatingunit of the following formula (9) and a repeating units of the followingformula (10), respectively:

    --Ar.sub.10 --CR.sub.1 ═CR.sub.2 --                    (9)

    --Ar.sub.11 --CR.sub.3 ═CR.sub.2 --                    (10)

wherein Ar₁₀ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-20 carbon atoms takingpart in the conjugated bonds and an at least 6-membered hetero-cyclicaromatic compound group having at least-one hetero atom and 4-18 carbonatoms; in the chemical structure of Ar₁₀, the number of the consecutiveatoms present in the shortest path between the two carbon atoms bondingto said two adjacent vinylene groups is 1, 3 or 5; Ar₁₁ is abifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 5-membered heterocyclic aromatic compound group having at leastone hetero atom and 4-18 carbon atoms; in the chemical structure ofAr₁₁, the total number of the consecutive carbon and nitrogen atomspresent in the shortest path between the two carbon atoms bonding tosaid two adjacent vinylene groups is an even number; and R₁, R₂, R₃ andR₄ are independently is a group selected from the group consisting of ahydrogen atom, a cyano group, an alkyl group of 1-20 carbon atoms and anaryl group of 6-18 carbon atoms; and at least one of Ar₁₀ and Ar₁₁ issubstituted by at least one of the group selected from the groupconsisting of an alkyl, alkoxyl or alkylthio group of 4-20 carbon atoms,an aryl or aryloxy group of 6-18 carbon atoms and a heterocyclicaromatic compound group of 4-14 carbon atoms.

(10) A polymeric fluorescent substance according to (9), wherein theAr₁₀ portion of formula (9) is selected from repeating units eachcontaining at least one of the structures represented by the followingformula (5): ##STR4## wherein R₅ to R₃₇ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms and a heterocyclic aromatic compoundgroup of 4-14 carbon atoms.

(11) A polymeric fluorescent substance according to (9) or (10), whichis a copolymer comprising a repeating unit represented by the followingformula (11) and a repeating unit represented by the following formula(12) with the molar ratio of the formula (11) repeating unit and theformula (12) repeating unit being 5:1 to 1:20: ##STR5## wherein X₃ is agroup selected from the group consisting of ##STR6## and R₅₈ to R₆₁ areindependently a group selected from the group consisting of a hydrogenatom, an alkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an arylor aryloxy group of 6-18 carbon atoms and a heterocyclic aromaticcompound group of 4-14 carbon atoms, and ##STR7## wherein R₆₂ to R₆₅ areindependently a group selected from the group consisting of a hydrogenatom, an alkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an arylor aryloxy group of 6-18 carbon atoms and a herterocyclic aromaticcompound group of 4-14 carbon atoms; and at least one of R₆₂ to R₆₅ is agroup selected from the group consisting of an alkyl, alkoxyl oralkylthio group of 4-20 carbon atoms, an aryl or aryloxy group of 6-18carbon atoms and is a heterocyclic aromatic compound group of 4-14carbon atoms.

(12) A polymeric fluorescent substance according to (9) or (10), whichis a copolymer further containing, in addition to the formula (11)repeating unit and the formula (12) repeating unit, a repeating unitrepresented by the following formula (13) with the molar ratio of theformula (11) repeating unit and the total of the repeating units offormulae (12) and (13) being 5:1 to 1:20 and the amount of the formula(12) repeating unit being at least 10 mole % based on the totalrepeating units: ##STR8## wherein R₆₆ to R₆₉ are independently a groupselected from the group consisting of a hydrogen atom and an alkyl,alkoxyl or alkylthio group of 1-3 carbon atoms.

(13) A polymeric fluorescent substance which is w soluble in solvents,emits a fluorescence in a solid state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and comprises a repeatingunit represented by the following formula (14): ##STR9## wherein Ar₁₂ isa bifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 5-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₂, the total number of the carbon andnitrogen atoms present in the shortest path between the two carbon atomsbonding to said two adjacent vinylene groups is an even number; Ar₁₃ isa bifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₃, the number of the consecutive atomspresent in the shortest path between the two carbon atoms bonding tosaid two adjacent vinylene groups is 1, 3 or 5.

(14) A polymeric fluorescent substance which is soluble in solvents,emits a fluorescence in a solid state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and comprises a repeatingunit represented by the following formula (15): ##STR10## wherein Ar₁₄is a bifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₄, the total number of the consecutiveatoms present in the shortest path between the two carbon atoms bondingto said two adjacent vinylene groups is 1, 3 or 5; Ar₁₅ is abifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 5-membered hetero-cyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₅, the total number of the carbon andnitrogen atoms present in the shortest path between the two carbon atomsbonding to said two adjacent vinylene groups is an even number.

(15) A polymeric fluorescent substance which is soluble in solvents,emits a fluorescence in a solid state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and is a copolymercomprising a repeating unit represented by the following formula (14)And a repeating unit represented by the following formula (16) with thetotal amount of the formula (14) repeating unit being at least 5 mole %of the total repeating units: ##STR11## wherein Ar₁₂ is a bifunctionalgroup forming a carbon--carbon bond with each of two adjacent vinylenegroups and is selected from the group consisting of an aromatic compoundgroup having 6-20 carbon atoms taking part in the conjugated bonds andan at least 5-membered hetero-cyclic aromatic compound group having atleast one hetero atom and 4-18 carbon atoms; in the chemical structureof Ar₁₂, the total number of the carbon and nitrogen atoms present inthe shortest path between the two carbon atoms bonding to said twoadjacent vinylene groups is an even number; Ar₁₃ is a bifunctional groupforming a carbon--carbon bond with each of two adjacent vinylene groupsand is selected from the group consisting of an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 6-membered heterocyclic aromatic compound group having at leastone hetero atom and 4-18 carbon atoms; in the chemical structure ofAr₁₃, the number of the consecutive atoms present in the shortest pathbetween the two carbon atoms bonding to said two adjacent vinylenegroups is 1, 3 or 5, and

    --Ar.sub.16 --CH═CH--                                  (16)

wherein Ar₁₆ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent substituted or unsubstituted vinylene groups and isselected from the group consisting of an aromatic compound group having6-22 carbon atoms taking part in the conjugated bonds and an at least5-membered heterocyclic aromatic compound group having at least onehetero atom and 4-20 carbon atoms; in the chemical structure of Ar₁₆,the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said two adjacentvinylene groups is an even number.

(16) A polymeric fluorescent substance which is soluble in solvents,emits a fluorescence in a solid state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and is a copolymercomprising a repeating unit represented by the following formula (15)and a repeating unit represented by the following formula (16) with theamount of the formula (15) repeating unit being at least 5 mole % of thetotal repeating units: ##STR12## wherein Ar₁₄ is a bifunctional groupforming a carbon--carbon bond with each of two adjacent vinylene groupsand is selected from the group consisting of an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 6-membered hetero-cyclic aromatic compound group having at leastone hetero atom and 4-18 carbon atoms; in the chemical structure ofAr₁₄, the total number of the consecutive atoms present in the shortestpath between the two carbon atoms bonding to said two adjacentvinylene,groups is 1, 3 or 5; Ar₁₅ is a bifunctional group forming acarbon--carbon bond with each of two adjacent vinylene groups and isselected from the group consisting of an aromatic compound group having6-20 carbon atoms taking part in the conjugated bonds and an at least5-membered heterocyclic aromatic compound group having at least onehetero atom and 4-18 carbon atoms; in the chemical structure of Ar₁₅,the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said two adjacentvinylene groups is an even number, and

    --Ar.sub.16 --CH═CH--                                  (16)

wherein Ar₁₆ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-22 carbon atoms takingpart in the conjugated bonds and an at least 5-membered heterocyclicaromatic compound group having at least one hetero atom and 4-20 carbonatoms; in the chemical structure of Ar₁₆, the total number of the carbonand nitrogen atoms present in the shortest path between the two carbonatoms bonding to said two adjacent vinylene groups is an even number.

(17) A polymeric fluorescent substance according to any one of (13),(14), (15) and (16), wherein the Ar₁₃ portion of formula (14) ##STR13##or the Ar₁₄ portion of formula (15) ##STR14## is selected from repeatingunits each containing one of the structures represented by the followingformula (5): ##STR15## wherein R₅ to R₃₇ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms and a heterocyclic aromatic compoundgroup of 4-14 carbon atoms.

(18) A polymeric fluorescent substance according to any one of (13),(14), (15), (16) and (17), wherein the Ar₁₂ portion of formula (14)##STR16## or the Ar₁₅ portion of formula (10) ##STR17## or the Ar₁₆portion of formula (16)

    --Ar.sub.16 --CH═CH--                                  (16)

comprises a repeating unit represented by the following formula (17) andthe Ar₁₃ portion of formula (14) or the Ar₁₄ portion of formula (15)comprises a repeating unit represented by the following formula (18):##STR18## wherein X₂ is a group selected from the group consisting ofC--R₅₇ and N; and R₅₀ to R₅₇ are independently a group selected from thegroup consisting of a hydrogen atom, a cyano group, an alkyl, alkoxyl oralkylthio group of 1-20 carbon atoms, an aryl or aryloxy group of 6-18carbon atoms and a heterocyclic aromatic compound group of 4-14 carbonatoms.

(19) An organic electroluminescence device according to (1), wherein thepolymeric fluorescent substance is a polymeric fluorescent substanceaccording to any one of (9) to (18).

PREFERRED EMBODIMENTS OF THE INVENTION

The organic EL devices of the present invention and the polymericfluorescent substances used therein are hereinafter described in detail.

The polymeric fluorescent substances used in the organic EL devices ofthe present invention, each contain at least one kind of repeating unitrepresented by formula (1) and at least one kind of repeating unitrepresented by formula (2) with the number of the formula (1) repeatingunits being 2-50%, preferably 5-30% of the total number of all therepeating units.

In the polymeric fluorescent substances, Ar₁ of formula (1) is abifunctional group forming a carbon--carbon bond with each of twoadjacent groups and is selected from the group consisting of an aromaticcompound group having 6-22 carbon atoms taking part in the conjugatedbonds, an at least 6-membered heterocyclic aromatic compound grouphaving a hetero atom(s) and 4-20 carbon atoms, and a group composed ofsaid aromatic compound group or said heterocyclic aromatic compoundgroup and a vinylene group; and in the chemical structure of Ar₁, thenumber of the consecutive atoms present in the shortest path between thetwo carbon atoms bonding to said two adjacent groups is 1, 3 or 5.

Specific examples of Ar₁ are bivalent aromatic compound groupsrepresented by formula (5), derivatives thereof, and arylene vinylenegroups each composed of one of the above groups and a substituted orunsubstituted vinylene group represented by the following formula (19):

    --CR.sub.70 ═CR.sub.71 --                              (19)

wherein R₇₀ and R₇₁ are independently a group selected from the groupconsisting of a hydrogen atom, a cyano group, an alkyl group of 1-20carbon atoms and an aryl group of 6-18 carbon atoms.

Of these, preferable are 1,3-phenylene group, naphthalene-1,3-diylgroup, pyridine-2,6-diyl group, quinoline-2,4-diyl group, arylenevinylene groups each composed of one of the above groups and a vinylenegroup, and groups each formed by attaching substituent(s) to one of theabove groups.

More preferable are 1,3-phenylene group, pyridine-2,6-diyl group,arylene vinylene groups each composed of one of the above groups and avinylene group, and groups formed by attaching a substituent(s) to oneof the above groups.

Ar₂ of formula (2) is a bifunctional group forming a carbon--carbon bondwith each of two adjacent groups and is selected from the groupconsisting of an aromatic compound group having 6-22 carbon atoms takingpart in the conjugated bonds, an at least 5-membered heterocyclicaromatic compound group having a hetero atom(s) and 4-20 carbon atoms,and a group composed of said aromatic w compound group or saidheterocyclic compound group and a vinylene group; and in the chemicalstructure of Ar₂, the total number of the carbon and nitrogen atomspresent in the shortest path between the two carbon atoms bonding tosaid two adjacent groups is an even number.

Specific examples of Ar₂ are bivalent aromatic compound groupsrepresented by the following formula (20), derivatives thereof, andarylene vinylene groups each composed of one of the above groups and asubstituted or unsubstituted vinylene group represented by the aboveformula (19): ##STR19## wherein R₇₂ to R₁₀₆ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms, and a heterocyclic aromatic compoundgroup of 4-14 carbon atoms.

Of these, preferable are 1,4-phenylene group, naphthalene-2,6-diylgroup, anthracene-9,10-diyl group, pyridine-2,5-diyl group,2,5-thienylene group, arylene vinylene groups each composed of one ofthe above groups and a vinylene group, and groups each formed byattaching a substituent(s) to one of the above groups.

More preferable are 1,4-phenylene group, pyridine-2,5-diyl group,2,5-thienylene group, arylene vinylene groups each composed of one ofthe above groups and a vinylene group, and groups each formed byattaching a substituent(s) to one of the above groups.

When the above repeating units are combined, larger repeating units areformed. For example, when a 1,4-phenylene group and a 1,4-phenylenevinylene group are combined, a 4,4'-biphenylene vinylene group isformed.

Mention is made on the substituent(s). The alkyl group of 1-20 carbonatoms includes methyl group, ethyl group, propyl group, butyl group,pentyl group, hexyl group, heptyl group, octyl group, decyl group,lauryl group, etc. Of these, preferable are methyl group, ethyl group,pentyl group, hexyl group, heptyl group and octyl group.

The alkoxyl group of 1-20 carbon atoms includes methoxyl group, ethoxylgroup, propoxyl group, butoxyl group, pentyloxy group, hexyloxy group,heptyloxy group, octyloxy group, decyloxy group, lauryloxy group, etc.Of these, preferable are methoxyl group, ethoxyl group, pentyloxy group,hexyloxy group, heptyloxy group and octyloxy group.

The alkylthio group includes methylthio group, ethylthio group,propylthio group, butylthio group, pentylthio group, hexylthio group,heptylthio group, octylthio group, decylthio group, laurylthio group,etc. Of these, preferable are methylthio group, ethylthio group,pentylthio group, hexylthio group, heptylthio group and octylthio group.

The aryl group is exemplified by phenyl group, 4-C₁ -C₁₂ alkoxyphenylgroups (C₁ -C₁₂ refers to 1-12 carbon atoms), 4-C₁ -C₁₂ alkylphenylgroups, 1-naphthyl group and 2-naphthyl group.

The aryloxy group is exemplified by phenoxy group.

The heterocyclic compound group is exemplified by 2-thienyl group,2-pyrrolyl group, 2-furyl group and 2-, 3- or 4-pyridyl group.

Next, description is made on the polymeric fluorescent substances of thepresent invention.

The polymeric fluorescent substances of the present invention aresoluble in solvents and have a number-average molecular weight of 10³-10⁷. They include a polymeric fluorescent substance which is acopolymer containing a repeating unit of formula (9) and a repeatingunit of formula (10); a polymeric fluorescent substance containing arepeating unit of formula (14) or a repeating unit of formula (15); apolymeric fluorescent substance which is a copolymer containing arepeating unit of formula (14) and a repeating unit of formula (16) withthe amount of the formula (14) repeating unit being 5 mole % or more ofthe total repeating units; a polymeric fluorescent substance which is acopolymer containing a repeating unit of formula (15) and a repeatingunit of formula (16) with the amount of the formula (15) repeating unitbeing 5 mole % or more of the total repeating units; a polymericfluorescent substance which is a copolymer containing a repeating unitof formula (11) and a repeating unit of formula (12) with the molarratio of the formula (11) repeating unit and the formula (12) repeatingunit being 5:1 to 1:20; and a polymeric fluorescent substance which is acopolymer containing a repeating unit of formula (11), a repeating unitof formula (12) and a repeating unit of formula (13) with the molarratio of the formula (11) repeating unit and the total of the formula(12) repeating unit and the formula (13) repeating unit being 5:1 to1:20 and the amount of the formula (12) repeating unit being 10 mole %or more of the total repeating units.

Herein, the number-average molecular weight refers to apolystyrene-reduced number-average molecular weight measured by gelpermeation chromatography (GPC) using chloroform as the solvent.

The polymeric fluorescent substance containing a repeating unit offormula (14) or formula (15), contains said repeating unit in an amountof preferably 10 mole % or more based on the total repeating units. Inview of the solubility of the polymeric fluorescent substance insolvents, at least one of Ar₁₀, Ar₁₁ [these are contained in the formula(14) repeating unit], Ar₁₂, Ar₁₃ [these are contained in the formula(15) repeating unit] and Ar₇ (contained in the formula (16) repeatingunit) preferably has at least one substituent selected from the groupconsisting of an alkyl, alkoxyl or alkylthio group of 4-20 carbon atoms,an aryl or aryloxy group of 6-18 carbon atoms and a heterocyclicaromatic compound group of 4-14 carbon atoms.

The substituent is exemplified by the following. The alkyl group of 4-20carbon atoms includes butyl group, pentyl group, hexyl group, heptylgroup, octyl group, decyl group, lauryl group, etc. of these, pentylgroup, hexyl group, heptyl group and octyl group are preferable.

The alkoxyl group of 4-20 carbon atoms includes butoxyl group, pentyloxygroup, hexyloxy group, heptyloxy group, octyloxy group, decyloxy group,lauryloxy group, etc. of these, pentyloxy group, hexyloxy group,heptyloxy group and octyloxy group are preferable.

The alkylthio group includes butylthio group, pentylthio group,hexylthio group, heptylthio group, octylthio group, decylthio group,laurylthio group, etc. Of these, pentylthio group, hexylthio group,heptylthio group and octylthio group are preferable.

The aryl group is exemplified by phenyl group, 4-C₁ --C₁₂ alkoxyphenylgroups (C₁ -C₁₂ refers to 1-12 carbon atoms), 4-C₁ -C₁₂ alkylphenylgroups, 1-naphthyl group and 2-naphthyl group.

The aryloxy group is exemplified by phenoxy group.

The heterocyclic aromatic compound group is exemplified by 2-thienylgroup, 2-pyrrolyl group, 2-furyl group and 2-, 3- or 4-pyridyl group.

The polymeric fluorescent substance containing a formula (11) repeatingunit and a formula (12) repeating unit contains said repeating units ina molar ratio of the formula (11) repeating unit and the formula (12)repeating unit, of preferably 1:1 to 1:10. The polymeric fluorescentsubstance containing repeating units of formula (11), formula (12) andformula (13) contains said repeating units in a molar ratio of theformula (11) repeating unit and the total of the other two repeatingunits, of preferably 1:1 to 1:10 and, in view of the solubility insolvents, contains the formula (12) repeating unit in an amount ofpreferably 30 mole % or more based on the total repeating units.

In order to obtain a high quantum yield of fluorescence, the polymericfluorescent substances of the present invention must contain a repeatingunit of formula (14), formula (15) or formula (11). By changing theratio of the formula (14) repeating unit and the formula (16) repeatingunit, or the ratio of the formula (15) repeating unit and the formula(16) repeating unit, or the ratio of the formula (8) repeating unit andthe total of the repeating units of formula (14) and formula (15), thepeak wavelength of fluorescence can be changed and accordingly a desiredfluorescence can be selected; therefore, use of two or more repeatingunits is advantageous.

The repeating unit of formula (11) is exemplified by 1,3-phenylenegroup, 5-alkyl-1,3-phenylene groups, 5-alkoxy-1,3-phenylene groups,pyridine-2,6-diyl group and 1-alkylpyridine-2,6-diyl groups. Of these,1,3-phenylene group and pyridine-2,6-diyl group are preferable.

The repeating unit of formula (12) is exemplified by 1,4-phenylenegroup, 2-alkyl-1,4-phenylene groups, 2-alkoxy-1,4-phenylene groups,2-alkylthio-1,4-phenylene groups, 2-aryl-1,4-phenylene groups,2-aryloxy-1,4-phenylene groups, 2,5-dialkyl-1,4-phenylene groups,2,5-dialkoxy-1,4-phenylene groups, 2,5-dialkylthio-1,4-phenylene groups,2,5-diaryl-1,4-phenylene groups, 2,5-diaryloxy-1,4-phenylene groups,2,6-dialkyl-1,4-phenylene groups, 2,6-dialkoxy-1,4-phenylene groups,2,6-dialkylthio-1,4-phenylene groups, 2,6-diaryl-1,4-phenylene groupsand 2, 6-diaryloxy-1,4-phenylene groups. Of these, preferable are1,4-phenylene group, 2,5-dialkyl-1,4-phenylene groups,2,5-dialkoxy-1,4-phenylene groups, 2,6-dialkyl-1,4-phenylene groups and2,6-dialkoxy-1,4-phenylene groups.

When the formula (12) repeating unit is a substituted repeating unit,the substituent(s) of said repeating unit is (are) described. The alkylgroup of 1-20 carbon atoms includes methyl group, ethyl group, propylgroup, butyl group, pentyl group, hexyl group, heptyl group, octylgroup, decyl group, lauryl group, etc. Of these, preferable are methylgroup, ethyl group, pentyl group, hexyl group, heptyl group and octylgroup.

The alkoxyl group of 1-20 carbon atoms includes methoxyl group, ethoxylgroup, propoxyl group, butoxyl group, pentyloxy group, hexyloxy group,heptyloxy group, octyloxy group, decyloxy group, lauryloxy group, etc.Of these, preferable are methoxy group, ethoxy group, pentyloxy group,hexyloxy group, heptyloxy group and octyloxy group.

The alkylthio group includes methylthio group, ethylthio group,propylthio group, butylthio group, pentylthio group, hexylthio group,heptylthio group, octylthio group, decylthio group, laurylthio group,etc. Of these, preferable are methylthio group, ethylthio group,pentylthio group, hexylthio group, hepthylthio group and octylthiogroup.

The aryl group is exemplified by phenyl group, 4-C₁ -C₁₂ alkoxyphenylgroups (C₁ -C₁₂ refers to 1-12 carbon atoms), 4-C₁ -C₁₂ alkylphenylgroups, 1-naphthyl group and 2-naphthyl group.

The aryloxy group is exemplified by phenoxy group.

The heterocyclic aromatic compound group is exemplified by 2-thienylgroup, 2-pyrrolyl group, 2-furyl group and 2-, 3- or 4-pyridyl group.

The repeating unit of formula (13) is exemplified by2-alkyl-1,4-phenylene groups, 2-alkoxy-1,4-phenylene groups,2-alkylthio-1,4-phenylene groups, 2-aryl-1,4-phenylene groups,2-aryloxy-1,4-phenylene groups, 2,5-dialkyl-1,4-phenylene groups,2,5-dialkoxy-1,4-phenylene groups, 2,5-dialkylthio-1,4-phenylene groups,2,5-diaryl-1,4-phenylene groups, 2,5-diaryloxy-1,4-phenylene groups,2,6-dialkyl-1,4-phenylene groups, 2,6-dialkoxy-1,4-phenylene groups,2,6-dialkylthio-1,4-phenylene groups, 2,6-diaryl-1,4-phenylene groupsand 2,6-diaryloxy-1,4-phenylene groups. Of these, preferable are2,5-dialkyl-1,4-phenylene groups, 2,5-dialkoxy-1,4-phenylene groups,2,6-dialkyl-1,4-phenylene groups and 2,6-dialkoxy-1,4-phenylene groups.

The polymeric fluorescent substances of the present invention arepolymers containing the above-mentioned repeating units, are soluble insolvents and, when made into a thin film, show a high quantum yield offluorescence.

The polymeric fluorescent substances of the present invention and thepolymeric fluorescent substances used in the organic EL devices of thepresent invention may each be a random, block or graft copolymer, or apolymer having a structure intermediate between those of saidcopolymers, for example, a block-type random copolymer. A block-typerandom copolymer or a block or graft copolymer is preferred to a whollyrandom copolymer, in order to obtain a high quantum yield offluorescence.

In the organic EL devices of the present invention, a luminescenceemitted from a thin film is utilized. Therefore, the polymericfluorescent substances used therein must emit a fluorescence in a solidstate.

The polymeric fluorescent substances of the present invention and thepolymeric fluorescent substances used in the organic EL devices of thepresent invention each have bent portions in the main chain and are notdifficult to dissolve in solvents for film making. However, in order toobtain a polymer having higher solubility in solvents and betterfilm-making property, it is preferable that each conjugated moiety ofthe main chain of the polymer has at least one aryl or heterocyclicaromatic compound group with its ring substituted with at least onesubstituent selected from the group consisting of alkyl, alkoxyl oralkylthio groups of 4-20 carbon atoms, aryl or aryloxy groups of 6-18carbon atoms and heterocyclic aromatic compound groups of 4-14 carbonatoms.

The substituents are exemplified by the followings. The alkyl group of4-20 carbon atoms includes butyl group, pentyl group, hexyl group,heptyl group, octyl group, decyl group, lauryl group, etc. Of these,preferable are pentyl group, hexyl group, heptyl group and octyl group.

The alkoxyl group of 4-20 carbon atoms includes butoxyl group, pentyloxygroup, hexyloxy group, heptyloxy group, octyloxy group, decyloxy group,lauryloxy group, etc. Of these, preferable are pentyloxy group, hexyloxygroup, heptyloxy group and octyloxy group.

The alkylthio group includes butylthio group, pentylthio group,hexylthio group, heptylthio group, octylthio group, decylthio group,laurylthio group, etc. Of these, preferable are pentylthio group,hexylthio group, hepthylthio group and octylthio group.

The aryl group is exemplified by phenyl group, 4-C₁ -C₁₂ alkoxyphenylgroups (C₁ -C₁₂ refers to 1-12 carbon atoms), 4-C₁ -C₁₂ alkylphenylgroups, 1-naphthyl group and 2-naphthyl group.

The aryloxy group is exemplified by phenoxy group.

The heterocyclic aromatic compound group is exemplified by 2-thienylgroup, 2-pyrrolyl group, 2-furyl group and 2-, 3- or 4-pyridyl group.

The number of the substituents varies depending upon the molecularweight of the desired polymer and the constitution of the repeatingunits contained in the polymer. However, in order to obtain a copolymerof high solubility, the number of the substituents is preferably one ormore per molecular weight of 600.

The good solvent for the polymeric fluorescent substances is exemplifiedby chloroform, methylene chloride, dichloroethane, tetrahydrofuran,toluene and xylene. Each polymeric fluorescent substance can bedissolved in each of these solvents in an amount of generally 0.1% byweight or more although the amount varies depending upon the structureand molecular weight of the polymer.

The polymerization degree of each polymeric fluorescent substance of thepresent invention or each polymeric fluorescent substance used in theorganic EL devices of the present invention is not particularlyrestricted as long as the polymer has a polystyrene-reduced molecularweight of 10³ -10⁷, and varies depending upon the constitution andproportions of the repeating units contained in the polymer. In view ofthe film-forming property of the polymer, the appropriate polymerizationdegree is generally 4-10,000, preferably 5-3,000, more preferably10-2,000 in terms of the total number of the repeating units.

Next are shown specific examples of the polymeric fluorescent substancesof the present invention.

Firstly, polymers each containing a repeating unit represented by thefollowing formula (21) are illustrated: ##STR20## wherein R₁₀₇ and R₁₀₈are selected from A0 to A59 (each is a combination of substituents) ofTable 1; R₁₀₉ to R₁₁₂ are selected form B0 to B3 (each is a combinationof substituents) of Table 2; and Ar₁₅ is selected from D0 to D8 (each isa substituent) of Table 3.

From A0 to A59, B0 to B3 and D0 to D8 are selected, respectively, An, Bmand Dl (n is a number of 0-59, m is a number of 0-3 and l is a number of0-8); an expression of repeating unit E ((n×4+m)×9+l) is used toindicate the combination of An, Bm and Dl; thus, repeating units E0 toE2159 are obtained. As a result, there are obtained polymers eachcontaining 5-1,000 units of one of E0 to E2159.

                  TABLE 1                                                         ______________________________________                                        No.     R.sub.107        R.sub.108                                            ______________________________________                                        A0      --H              --C.sub.5 H.sub.11                                     A1 --H --C.sub.6 H.sub.13                                                     A2 --H --C.sub.7 H.sub.15                                                     A3 --H --C.sub.8 H.sub.17                                                     A4 --H --C.sub.10 H.sub.21                                                    A5 --H --C.sub.12 H.sub.25                                                    A6 --H --C.sub.14 H.sub.29                                                    A7 --CH.sub.3 --C.sub.5 H.sub.11                                              A8 --CH.sub.3 --C.sub.6 H.sub.13                                              A9 --CH.sub.3 --C.sub.7 H.sub.15                                              A10 --CH.sub.3 --C.sub.8 H.sub.17                                             A11 --CH.sub.3 --C.sub.10 H.sub.21                                            A12 --CH.sub.3 --C.sub.12 H.sub.25                                            A13 --CH.sub.3 --C.sub.14 H.sub.29                                            A14 --C.sub.2 H.sub.5 --C.sub.5 H.sub.11                                      A15 --C.sub.2 H.sub.5 --C.sub.6 H.sub.13                                      A16 --C.sub.2 H.sub.5 --C.sub.7 H.sub.15                                      A17 --C.sub.2 H.sub.5 --C.sub.8 H.sub.17                                      A18 --C.sub.2 H.sub.5 --C.sub.10 H.sub.21                                     A19 --C.sub.2 H.sub.5 --C.sub.12 H.sub.25                                     A20 --C.sub.2 H.sub.5 --C.sub.14 H.sub.29                                     A21 --C.sub.5 H.sub.11 --C.sub.5 H.sub.11                                     A22 --C.sub.6 H.sub.13 --C.sub.6 H.sub.13                                     A23 --C.sub.7 H.sub.15 --C.sub.7 H.sub.15                                     A24 --C.sub.8 H.sub.17 --C.sub.8 H.sub.17                                     A25 --C.sub.10 H.sub.21 --C.sub.10 H.sub.21                                   A26 --C.sub.12 H.sub.25 --C.sub.12 H.sub.25                                   A27 --C.sub.14 H.sub.29 --C.sub.14 H.sub.29                                    - A28 --H                                                                                           1  STR21##                                              - A29                                                                                               1  STR22##                                                                    1  STR23##                                              - A30 --H --OC.sub.5 H.sub.11                                                A31 --H --OC.sub.6 H.sub.13                                                   A32 --H --OC.sub.7 H.sub.15                                                   A33 --H --OC.sub.8 H.sub.17                                                   A34 --H --OC.sub.10 H.sub.21                                                  A35 --H --OC.sub.12 H.sub.25                                                  A36 --H --OC.sub.14 H.sub.29                                                  A37 --OCH.sub.3 --OC.sub.5 H.sub.11                                           A38 --OCH.sub.3 --OC.sub.6 H.sub.13                                           A39 --OCH.sub.3 --OC.sub.7 H.sub.15                                           A40 --OCH.sub.3 --OC.sub.8 H.sub.17                                           A41 --OCH.sub.3 --OC.sub.10 H.sub.21                                          A42 --OCH.sub.3 --OC.sub.12 H.sub.25                                          A43 --OCH.sub.3 --OC.sub.14 H.sub.29                                          A44 --OC.sub.2 H.sub.5 --OC.sub.5 H.sub.11                                    A45 --OC.sub.2 H.sub.5 --OC.sub.6 H.sub.13                                    A46 --OC.sub.2 H.sub.5 --OC.sub.7 H.sub.15                                    A47 --OC.sub.2 H.sub.5 --OC.sub.8 H.sub.17                                    A48 --OC.sub.2 H.sub.5 --OC.sub.10 H.sub.21                                   A49 --OC.sub.2 H.sub.5 --OC.sub.12 H.sub.25                                   A50 --OC.sub.2 H.sub.5 --OC.sub.14 H.sub.29                                   A51 --OC.sub.5 H.sub.11 --OC.sub.5 H.sub.11                                   A52 --OC.sub.6 H.sub.13 --OC.sub.6 J.sub.13                                   A53 --OC.sub.7 H.sub.15 --OC.sub.7 H.sub.15                                   A54 --OC.sub.8 H.sub.17 --OC.sub.8 H.sub.17                                   A55 --OC.sub.10 H.sub.21 --OC.sub.10 H.sub.21                                 A56 --OC.sub.12 H.sub.25 --OC.sub.12 H.sub.25                                 A57 --OC.sub.14 H.sub.29 --OC.sub.14 H.sub.29                                  - A58 --H                                                                                           2  STR24##                                              - A59                                                                                               2  STR25##                                                                    2  STR26##                                           ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        No.   R.sub.109                                                                             R.sub.110    R.sub.111   R.sub.112                              ______________________________________                                        B0    --H     --H          --H         --H                                      B1 --H --CN --CN --H                                                          B2 --H --CH.sub.3 --CH.sub.3 --H                                               - B3 --H                                                                                                          1  STR27##                                                                    1  --H28##                             ______________________________________                                    

                                      TABLE 3                                     __________________________________________________________________________    D0          D1         D2          D3                                         __________________________________________________________________________                                       3  STR29##                                                                    4  STR30##                                                                    5  STR31##                                                                    6  STR32##                                 __________________________________________________________________________    D4         D5       D6       D7       D8                                      __________________________________________________________________________                                          7  STR33##                                                                    8  STR34##                                                                    9  STR35##                                                                    0  STR36##                                                                    1  STR37##                              __________________________________________________________________________

Then, copolymers each containing the formula (21) repeating unit and arepeating unit of the following formula (22) are illustrated: ##STR38##wherein R₁₁₃ and R₁₁₄ are selected from F0 to F59 (each is a combinationof substituents) of Table 4; R₁₁₅ to R₁₁₈ are selected from G0 to G3(each is a combination of substituents) of Table 5; and Ar₁₆ is selectedfrom H0 to H13 (each is a substituent) of Table 6.

From F0 to F59, G0 to G3 and H0 to H13 are selected, respectively, Fp,Gq and Hr (p is a number of 0-59, q is a number of 0-3 and r is a numberof 0-13); an expression of I ((p×4+q)×14+r) is used to indicate thecombination of Fp, Gq and Hr; thus, repeating units I0 to I3119 areobtained. From E0 to E2159 (previously described) and I0 to I3119 areselected each one repeating unit, i.e. Es and It (s is 0-2159 and t is0-3119). By copolymerizing Es and It, fluorescent copolymers J0 toJ6739199 are obtained when the combination of Es and It is indicated asJ (s×3120+t). The copolymers are random copolymers in which the ratio ofthe Es number and the It number is 1:0 to 1:24, or alternatingcopolymers composed of Es and It.

                  TABLE 4                                                         ______________________________________                                        No.      R.sub.113        R.sub.114                                           ______________________________________                                        F0       --H              --C.sub.5 H.sub.11                                    F1 --H --C.sub.6 H.sub.13                                                     F2 --H --C.sub.7 H.sub.15                                                     F3 --H --C.sub.8 H.sub.17                                                     F4 --H --C.sub.10 H.sub.21                                                    F5 --H --C.sub.12 H.sub.25                                                    F6 --H --C.sub.14 H.sub.29                                                    F7 --CH.sub.3 --C.sub.5 H.sub.11                                              F8 --CH.sub.3 --C.sub.6 H.sub.13                                              F9 --CH.sub.3 --C.sub.7 H.sub.15                                              F10 --CH.sub.3 --C.sub.8 H.sub.17                                             F11 --CH.sub.3 --C.sub.10 H.sub.21                                            F12 --CH.sub.3 --C.sub.12 H.sub.25                                            F13 --CH.sub.3 --C.sub.14 H.sub.29                                            F14 --C.sub.2 H.sub.5 --C.sub.5 H.sub.11                                      F15 --C.sub.2 H.sub.5 --C.sub.6 H.sub.13                                      F16 --C.sub.2 H.sub.5 --C.sub.7 H.sub.15                                      F17 --C.sub.2 H.sub.5 --C.sub.8 H.sub.17                                      F18 --C.sub.2 H.sub.5 --C.sub.10 H.sub.21                                     F19 --C.sub.2 H.sub.5 --C.sub.12 H.sub.25                                     F20 --C.sub.2 H.sub.5 --C.sub.14 H.sub.29                                     F21 --C.sub.5 H.sub.11 --C.sub.5 H.sub.11                                     F22 --C.sub.6 H.sub.13 --C.sub.6 H.sub.13                                     F23 --C.sub.7 H.sub.15 --C.sub.7 H.sub.15                                     F24 --C.sub.8 H.sub.17 --C.sub.8 H.sub.17                                     F25 --C.sub.10 H.sub.21 --C.sub.10 H.sub.21                                   F26 --C.sub.12 H.sub.25 --C.sub.12 H.sub.25                                   F27 --C.sub.14 H.sub.29 --C.sub.14 H.sub.29                                    - F28 --H                                                                                            1  STR39##                                             - F29                                                                                                1  STR40##                                                                    1  STR41##                                            F30 --H --OC.sub.5 H.sub.11                                                   F31 --H --OC.sub.6 H.sub.13                                                   F32 --H --OC.sub.7 H.sub.15                                                   F33 --H --OC.sub.8 H.sub.17                                                   F34 --H --OC.sub.10 H.sub.21                                                  F35 --H --OC.sub.12 H.sub.25                                                  F36 --H --OC.sub.14 H.sub.29                                                  F37 --OCH.sub.3 --OC.sub.5 H.sub.11                                           F38 --OCH.sub.3 --OC.sub.6 H.sub.13                                           F39 --OCH.sub.3 --OC.sub.7 H.sub.15                                           F40 --OCH.sub.3 --OC.sub.8 H.sub.17                                           F41 --OCH.sub.3 --OC.sub.10 H.sub.21                                          F42 --OCH.sub.3 --OC.sub.12 H.sub.25                                          F43 --OCH.sub.3 --OC.sub.14 H.sub.29                                          F44 --OC.sub.2 H.sub.5 --OC.sub.5 H.sub.11                                    F45 --OC.sub.2 H.sub.5 --OC.sub.6 H.sub.13                                    F46 --OC.sub.2 H.sub.5 --OC.sub.7 H.sub.15                                    F47 --OC.sub.2 H.sub.5 --OC.sub.8 H.sub.17                                    F48 --OC.sub.2 H.sub.5 --OC.sub.10 H.sub.21                                   F49 --OC.sub.2 H.sub.5 --OC.sub.12 H.sub.25                                   F50 --OC.sub.2 H.sub.5 --OC.sub.14 H.sub.29                                   F51 --OC.sub.5 H.sub.11 --OC.sub.5 H.sub.11                                   F52 --OC.sub.6 H.sub.13 --OC.sub.6 J.sub.13                                   F53 --OC.sub.7 H.sub.15 --OC.sub.7 H.sub.15                                   F54 --OC.sub.8 H.sub.17 --OC.sub.8 H.sub.17                                   F55 --OC.sub.10 H.sub.21 --OC.sub.10 H.sub.21                                 F56 --OC.sub.12 H.sub.25 --OC.sub.12 H.sub.25                                 F57 --OC.sub.14 H.sub.29 --OC.sub.14 H.sub.29                                  - F58 --H                                                                                            2  STR42##                                             - F59                                                                                                2  STR43##                                                                    2  STR44##                                          ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        No.  R.sub.115                                                                             R.sub.116     R.sub.117   R.sub.118                              ______________________________________                                        G0   --H     --H           --H         --H                                      G1 --H --CN --CN --H                                                          G2 --H --CH.sub.3 --CH.sub.3 --H                                              G3 --H                                                                                                             1  STR45##                                                                    1  --H46##                             ______________________________________                                    

                                      TABLE 6                                     __________________________________________________________________________    H0           H1           H2         H3                                       __________________________________________________________________________                                         3  STR47##                                                                    4  STR48##                                                                    5  STR49##                                                                    6  STR50##                               __________________________________________________________________________    H4              H5         H6                                                 __________________________________________________________________________                               7  STR51##                                                                    8  STR52##                                                                    9  STR53##                                         __________________________________________________________________________    H7                H8                H9                                        __________________________________________________________________________                                        0  STR54##                                                                    1  STR55##                                                                    2  STR56##                                __________________________________________________________________________    H10           H11          H12        H13                                     __________________________________________________________________________                                          3  STR57##                                                                    4  STR58##                                                                    5  STR59##                                                                    6  STR60##                              __________________________________________________________________________

Use of the above-mentioned polymeric fluorescent substance in productionof an organic EL device is very advantageous because the polymericfluorescent substance is soluble in organic solvents and the resultingsolution can be easily made into a thin film simply by coating andsubsequent drying to remove the solvent. This simple operation can alsobe applied when a charge transport compound is added to the polymericfluorescent substance.

The process for synthesis of the polymeric fluorescent substance used inthe organic EL device of the present invention is not particularlyrestricted. However, as one process, there can be cited, for example, aWittig reaction between a dialdehyde compound in which two aldehydegroups are attached to a repeating unit of formula (1) and adiphosphonium salt obtained from triphenylphosphine and a compound inwhich two halogenated methyl groups are attached to a repeating unit offormula (2).

In the reaction, the dialdehyde compound and the diphosphonium salt canbond directly to each other, but the two molecules of any one compounddo not bond directly to each other. Therefore, by adding a dialdehydecompound in which two aldehyde groups are attached to a repeating unitof formula (2) to change the proportions of two dialdehyde compounds,the substantial length of conjugated chain in the polymeric fluorescentsubstance obtained can be controlled as desired.

As another process, there can be cited a dehydrohalogenation processwhich comprises subjecting to dehydrohalogenation a compound in whichtwo halogenated methyl groups are attached to both ends of an aromaticoligomer containing a repeating unit of formula (1) and a compound inwhich two halogenated methyl groups are attached to a repeating unit offormula (2).

There can also be cited a sulfonium salt decomposition process whichcomprises alkali-polymerizing a compound which is a formula (1)repeating unit-containing aromatic oligomer having a sulfonium saltstructure at both ends, to form an intermediate and heat-treating theintermediate to obtain a polymeric fluorescent substance.

Of these processes, the process using the Wittig reaction is preferablein view of the reaction control and yield.

With respect to the process for synthesis of a polymeric fluorescentsubstance having a cyanovinyl group, there is no particular restriction.However, there can be used, for example, a process similar to thosedescribed in J. Org. Chem., Vol. 25, p. 813 (1959); Makromol. Chem.,Vol. 74, p. 71 (1964); etc.

For example, there can be cited a Knoevenagel reaction which comprisespolymerizing a corresponding diacetonitrile (specifically,m-phenylenediacetonitrile, for example) and a corresponding dialdehydecompound (specifically, 2,5-dioctyloxyterephthalaldehyde, for example)in, for example, a mixed solvent of ethyl alcohol and chloroform in thepresence of sodium methoxide. In order to obtain a copolymer, it ispossible to react two or more diacetonitriles and/or two or moredialdehyde compounds.

Since each of the Wittig reaction and the Knoevenagel reaction can beconducted using lithium ethoxide or the like, a reaction using adialdehyde compound(s), a diphosphonium compound(s) and a diacetonitrilecompound(s) in appropriate amounts can produce a copolymer of all ofthese monomers.

More specific description is made on a process for synthesis of anarylene vinylene copolymer which is an example of the polymericfluorescent substances used in the organic EL devices of the presentinvention.

When an arylene vinylene copolymer is for example obtained by a Wittigreaction, a bis(halogenated methyl) compound (e.g.2,5-dioctyloxy-p-xylilene dibromide) is for example reacted withtriphenylphosphine in N,N-dimethylformamide, a solvent, to synthesize aphosphonium salt, and this salt is subjected to condensation with adialdehyde compound containing a formula (1) structure, for example,isophthalaldehyde in, for example, ethyl alcohol in the presence oflithium ethoxide to obtain an arylene vinylene copolymer having a1,3-phenylene group. Addition, in this case , of a dialdehyde compoundcontaining a formula (2) structure, specifically, terephthalaldehyde,can produce a copolymer having a longer conjugated chain. In order toobtain a copolymer, two or more diphosphonium salts and/or two or moredialdehyde compounds may be reacted.

When the thus-produced polymer is used as a light emitting material ofan organic EL device, the purity of the polymer has an influence on theluminous property of the device. It is, therefore, desirable that thepolymer after synthesis is subjected to purification treatments such asreprecipitation, chromatographic separation and the like.

Regarding the structure of the organic EL device produced by using thepolymeric fluorescent substance of the present invention, no specificrestrictions are imposed and a known structure can be employed as longas a light emitting material comprising said polymeric fluorescentsubstance is used in the light emitting layer provided between a pair ofelectrodes at least one of which is transparent or semi-transparent.

Examples of said structure includes one in which a pair of electrodesare provided on both sides of the light emitting layer comprising thepolymeric fluorescent substance or comprising a mixture of the polymericfluorescent substance and a charge transport material, which is ageneric name for electron transport material and hole transportmaterial, and one in which an electron transport layer containing anelectron transport material is laminated between a cathode and a lightemitting layer in adjacency to the light emitting layer and/or in whicha hole transport layer containing a hole transport material is laminatedbetween an anode and a light emitting layer in adjacency to the lightemitting layer.

The light emitting layer and the charge transport layer may each beprovided as a single layer or as a combination of two or more layers,all of which embodiments are embraced in the scope of the presentinvention. Further, a light emitting material (or materials) other thanthe polymeric fluorescent substance, such as mentioned below, may bemixed in the light emitting layer. Also, the light emitting layer and/orcharge transport layer may be formed by dispersing the polymericfluorescent substance and/or charge transport material in a polymericcompound.

As for the charge transport material, i.e. electron transport materialor hole transport material, used with a polymeric fluorescent substanceof the present invention, such a material is not specified and knowntypes can be used in the present invention. For example, as the holetransport material, there can be used pyrazoline derivatives, arylaminederivatives, stilbene derivatives, triphenyldiamine derivatives, etc. Asthe electron transport material, there can be used oxadiazolederivatives, anthraquinodimethane and its derivatives, benzoquinone andits derivatives, naphthoquinone and its derivatives, anthraquinone andits derivatives, tetracyanoanthraquinodimethane and its derivatives,fluorenone derivatives, diphenyldicyanoethylene and its derivatives,diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline andits derivatives, etc.

More concrete examples of these materials are shown in JP-A-63-70257,JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209988,JP-A-3-37992 and JP-A-3-152184. As the hole transport material,triphenyldiamine derivatives are preferably used, and as the electrontransport material, oxadiazole derivatives, benzoquinone and itsderivatives, anthraquinone and its derivatives, and metal complexes of8-hydroxyquinoline and its derivatives are preferably used. Morespecifically, 4,4'-bis(N-(3-methylphenyl)-N-phenylamino)-biphenyl ispreferred as the hole transport material, and2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, benzoquinone,anthraquinone and tris(8-quinolinol)aluminum are preferred as theelectron transport material.

In the present invention, one of these electron transport and holetransport compounds may be used, or both of electron transport and holetransport compounds may be used together. Also, these compounds may beused either singly or as a mixture of two or more of them.

When a charge transport layer is provided between a light emitting layerand an electrode, it is formed by using the above-mentioned chargetransport material(s).

When a charge transport material is mixed in the light emitting layer,the amount thereof used varies depending upon the type of the compoundused and other factors, so that it is properly decided considering thesefactors within such an amount range as the film-forming property and theluminous property of the compound are not impaired. Usually, the chargetransport material is used in an amount of 1 to 40% by weight,preferably 2-30% by weight based on the light emitting material.

The light emitting material usable with a polymeric fluorescentsubstance of the present invention is not specified; for example, therecan be used naphthalene derivatives, anthracene and its derivatives,perylene and its derivatives, dyes such as polymethine dyes, xanthenedyes, coumarin dyes and cyanine dyes, metal complexes of8-hydroxyquinoline and its derivatives, aromatic amines,tetraphenylcyclopentadiene and its derivatives, tetraphenylbutadiene andits derivatives. More specifically, known light emitting materials, forexample, those mentioned in JP-A-57-51781 and JP-A-59-194393 can beused.

A typical process for producing an organic EL device using a polymericfluorescent substance of the present invention is described below.

A pair of transparent or semi-transparent electrodes, consisting of ananode and a cathode, are provided on a transparent substrate made ofglass, transparent plastic or the like.

As the anode material, a conducting metal oxide film, a semi-transparentthin metallic film or the like is used. Specifically, a film ofindium-tin-oxide (ITO), tin oxide or the like, or a film of Au, Pt, Ag,Cu or the like is used. The film is formed by a known film formingtechnique such as vacuum deposition, sputtering, plating or the like.

On this anode is formed a light emitting layer containing, as a lightemitting material, the above-mentioned polymeric fluorescent substanceor said substance and a charge transport material. This light emittinglayer can be formed by coating the light emitting material in the formof a melt, a solution or a solution of a mixture of the polymericfluorescent substance and the charge transport material by a knowncoating method such as spin coating, casting, dipping, bar coating, rollcoating or the like. Preferably, a film is formed by coating the abovesolution or solution of mixture by spin coating, casting, dipping, barcoating, roll coating or the like.

The thickness of the light emitting layer is 1 nm to 1 μm, preferably 2to 500 nm. A thickness in the range of 5 to 100 nm is preferred forincreasing current density to elevate luminous efficiency.

When a thin film is formed by said coating method, the film ispreferably dried by heating at 30-300° C., preferably 60-200° C., underreduced pressure or in an inert atmosphere for removing the solvent.

When said light emitting layer is laminated on a charge transport layer,which is a generic name for hole transport layer and electron transportlayer, it is preferable that a hole transport layer is formed on theanode before the light emitting layer is provided by the above coatingmethod, and/or after the light emitting layer is provided, an electrontransport layer is formed thereon.

The method for forming the charge transport layer is not specified inthe present invention; for example, the charge transport layer may beformed by vacuum deposition of a charge transport material in a powderyform, or by coating a solution of said material by an appropriatecoating method such as spin coating, casting, dipping, bar coating, rollcoating or the like, or by mixing and dispersing a polymeric compoundand a charge transport material in a molten state or a state of solutionand then coating the suspension by a suitable coating method such asspin coating, casting, dipping, bar coating, roll coating or the like.The polymeric compound to be mixed is not specified, but it ispreferably a polymer which does not impede charge transport to anysignificant degree. Also, a polymer which does not have strong visiblelight absorbance is preferably used.

A polymer having a charge-transporting property can be used in thecharge transport layer without mixing with a low-molecular-weight chargetransport material.

Examples of the polymeric compound having a charge-transporting propertyare poly(N-vinylcarbazole), polyaniline and its derivatives,polythiophene and its derivatives, poly(p-phenylene vinylene) and itsderivatives, poly(2,5-thienylene vinylene) and its derivatives. Examplesof the polymeric compound not having a charge-transporting property arepolycarbonates, polyacrylates, polymethyl acrylate, polymethylmethacrylate, polystyrenes, polyvinyl chloride, and polysiloxanes. Forforming the film, a coating method is preferably employed because ofeasy formation of the film.

The thickness of the-charge transport layer needs to be large enough toprevent formation of pinholes, but too large a thickness is undesirablebecause it increases device resistance, requiring a high drive voltage.In view of this, the recommended thickness of the charge transport layeris 1 nm to 1 μm, preferably 2 to 500 nm, more preferably 5 to 100 nm.

Then an electrode is provided on the light emitting layer or electrontransport layer. This electrode serves as an electron injection cathode.The material thereof is not specified, but a material with small workfunction is preferred. There can be used, for example, Al, In, Mg, Ca,Li, Mg--Ag alloy, In--Ag alloy, Mg--In alloy, Mg--Al alloy, Mg--Lialloy, Al--Li alloy and graphite thin film. Vacuum deposition,sputtering or other suitable techniques may be used for forming thecathode.

The most remarkable feature of the polymeric fluorescent substances ofthe present invention in use as a light emitting material is thatbecause of relatively high melting point and decomposition temperature,it is thermally stable, high in quantum yield of fluorescence andcapable of forming a highly homogeneous light emitting layer with easeby a coating method, and it therefore allows very easy manufacture ofhigh-luminance organic EL devices.

The present invention is hereinafter described in more detail by way ofExamples. However, the present invention is not restricted to theseExamples.

Herein, number-average molecular weight refers to a polystyrene-reducednumber-average molecular weight as measured by gel permeationchromatography (GPC) using chloroform as a solvent.

EXAMPLE 1

[Synthesis of Polymeric Fluorescent Substance 1]

2,5-Dioctyloxy-p-xylylene dibromide was reacted with triphenylphosphinein N,N-dimethylformamide, a solvent, to synthesize a phosphonium salt.In ethyl alcohol were dissolved 9.56 parts by weight of the phosphoniumsalt, 0.268 part by weight of isophthalaldehyde and 1.07 parts by weightof terephthalaldehyde. To the resulting solution was dropwise added anethyl alcohol solution containing 1.56 parts by weight of lithiumethoxide. The mixture was subjected to polymerization at roomtemperature for 3 hours and allowed to stand overnight at roomtemperature. The resulting precipitate was collected by filtration,washed with ethyl alcohol, and dissolved in chloroform. To the solutionwas added ethanol for reprecipitation. The resulting precipitate wasdried under reduced pressure to obtain 3.64 parts by weight of apolymer. This polymer is referred to as polymeric fluorescent asubstance 1. The repeating units of the polymeric fluorescent substance1 and the molar ratio thereof which was calculated from the ratio of theamounts of the monomers fed, are shown below. ##STR61##

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 1 was 9.8×10³. The measured elemental analysisvalues of the polymeric fluorescent substance 1 were 83.0% by weightcarbon, 9.4% by weight hydrogen, less than 0.3% by weight nitrogen andless than 0.2% by weight chlorine and almost agreed with the calculatedvalues. An NMR analysis confirmed that the observed hydrogen signalsalmost correspond to the structural formula obtained. Also, in the IRabsorption spectrum of the polymeric fluorescent substance 1, the intakeof isophthalaldehyde into said polymer was confirmed from the presenceof an absorption peak due to m-substituted benzene.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 1 could easily be dissolved inchloroform. A 0.05% chloroform solution of this polymeric fluorescentsubstance was spin-coated on a quartz plate to form a thin film of saidpolymer. The ultraviolet-visible light absorption spectrum andfluorescence spectrum of this thin film were measured bySpectrophotometer UV365 of Shimadzu Seisakusho K.K. andFluorospectrophotometer 850 of Hitachi Ltd. The fluorescence spectrum ofthe film when excited at 410 nm was used for calculation of quantumyield of fluorescence. Intensity of fluorescence was obtained as arelative value determined by dividing the area of fluorescence spectrumplotted with abscissa used for wavenumber, by an absorbance at 410 nm.The fluorescence intensity, which is relative value of quantum yield offluorescence, of the thin film of the polymeric fluorescent substance 1was high as seen from Table 7.

[Manufacture and Evaluation of EL Device]

On a glass substrate having a 40-nm thick ITO film formed by sputteringwas dip-coated a 1.0% by weight chloroform solution of the polymericfluorescent substance 1 to form a 50-nm thick film on said substrate.The coating film was dried in vacuo at 80° C. for 1 hour. Thereon wasvapor-deposited tris(8-quinolinol)-aluminum (Alq₃) at a rate of 0.1-0.2nm/sec to form a 70-nm thick electron transport layer. Lastly, amagnesium-silver alloy (Mg:Ag=9:1 by weight) was vapor-deposited thereonas a cathode in a thickness of 150 nm to make an organic EL device. Thedegree of vacuum in vapor deposition was below 8×10⁻⁶ Torr in all cases.

When a voltage of 10.5 V was applied to this device, a flow ofelectricity with a current density of 126 mA/cm² was induced and ayellowish green electro-luminescence with a luminance of 1,037 cd/m² wasobserved. In this case, the luminous efficiency was 0.82 cd/A. Theluminance was almost proportional to the current density. Increase incurrent density showed the highest luminance of 10,578 cd/m². The ELpeak wavelength was 538 nm, which almost agreed with the peak wavelengthof fluorescence of the thin film of polymeric fluorescent substance 1,whereby electroluminescence from the polymeric fluorescent substance 1was confirmed.

EXAMPLE 2

[Synthesis of Polymeric Fluorescent Substance 2]

Synthesis, washing and reprecipitation were conducted in the same manneras in Example 1 except that there were used 0.671 part by weight ofisophthalaldehyde and 0.671 part by weight of terephthalaldehyde,whereby 3.49 parts by weight of a polymer was obtained. The polymer isreferred to as polymeric fluorescent substance 2. The repeating units ofthe polymeric fluorescent substance 2 and the molar ratio thereof whichwas calculated from the ratio of the amounts of the monomers fed, areshown below. ##STR62##

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 2 was 9.8×10³. The measured elemental analysisvalues of the polymeric fluorescent substance 2 were 83.0% by weightcarbon, 9.4% by weight hydrogen, less than 0.3% by weight nitrogen andless than 0.2% by weight chlorine and almost agreed with the calculatedvalues. An NMR analysis confirmed that the observed hydrogen signalsalmost correspond to the structural formula obtained. Also, in the IRabsorption spectrum of the polymeric fluorescent substance 2, the intakeof isophthalaldehyde into said polymer was confirmed from the presenceof an absorption peak due to m-substituted benzene.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 2 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 2 was high asseen from Table 7.

[Manufacture and Evaluation of EL Device]

An EL device was manufactured in the same manner as in Example 1 exceptthat the polymeric fluorescent substance 2 was used in place of thepolymeric fluorescent substance 1.

When a voltage of 12.3 V was applied to this device, a flow ofelectricity with a current density of 0.789 mA/cm² was induced and agreen electroluminescence with a luminance of 14.4 cd/m² was observed.In this case, the luminous efficiency was 1.83 cd/A. The luminance wasalmost proportional to the current density. The EL peak wavelength was530 nm, which almost agreed with the peak wavelength of fluorescence ofthe thin film of polymeric fluorescent substance 2, wherebyelectroluminescence from the polymeric fluorescent substance 2 wasconfirmed.

COMPARATIVE EXAMPLE 1

[Synthesis of Polymeric Fluorescent Substance 3]

2,5-Diheptyloxy-p-xylylene dibromide was reacted with triphenylphosphinein N,N-dimethylformamide, a solvent, to synthesize a phosphonium salt.In ethyl alcohol were dissolved 7.4 parts by weight of the phosphoniumsalt and 1 part by weight of terephthalaldehyde. To the solution wasdropwise added an ethyl alcohol solution containing 0.9 part by weightof lithium ethoxide. The mixture was subjected to polymerization at roomtemperature for 3 hours and then allowed to stand overnight at roomtemperature. The resulting precipitate was collected by filtration,washed with ethyl alcohol and dissolved in chloroform. To the solutionwas added ethanol for reprecipitation. The resulting precipitate wasdried under reduced pressure to obtain 1.5 parts by weight of a polymer.This polymer is referred to as polymeric fluorescent substance 3. Therepeating units of the polymeric fluorescent substance 3 and the molarratio thereof which was calculated from the ratio of the amounts of themonomers fed, are shown below. ##STR63## The polymeric fluorescentsubstance 3 was an alternating copolymer composed of these two repeatingunits.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 3 was 1.0×10⁴. The measured elemental analysisvalues of the polymeric fluorescent substance 3 were 82.9% by weightcarbon, 9.3% by weight hydrogen, less than 0.3% by weight nitrogen andless than 0.2% by weight bromine and almost agreed with the calculatedvalues. An NMR analysis confirmed that the observed hydrogen signalsalmost correspond to the structural formula obtained.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 3 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum in the same manner as in Example 1. The fluorescence intensityof the polymeric fluorescent substance 3 was lower than that of thepolymeric fluorescent substance 1 of Example 1, as seen from Table 7.

[Manufacture and Evaluation of EL Device]

An EL device was manufactured in the same manner as in Example 1 exceptthat the polymeric fluorescent substance 3 was used in place of thepolymeric fluorescent substance 1.

When a voltage of 10.5 V was applied to this device, a flow ofelectricity with a current density of 20.5 mA/cm² was induced and ayellowish green electroluminescence with a luminance of 98.0 cd/m² wasobserved. In this case, the luminous efficiency was 0.48 cd/A. Theluminance was almost proportional to the current density. Increase incurrent density showed the highest luminance of 2,770 cd/m². The EL peakwave-length was about 550 nm, which almost agreed with the peakwavelength of fluorescence of the thin film of polymeric fluorescentsubstance 3, whereby electro-luminescence from the polymeric fluorescentsubstance 3 was confirmed.

                                      TABLE 7                                     __________________________________________________________________________    EL properties                                                                                        Luminous                                                                           EL peak                                                                             Quantum yield                                 Voltage Current density Luminance efficiency wavelength of fluorescence       (v) (mA/cm.sup.2) (cd/m.sup.2) (cd/A) (nm) (arbitrary unit)                 __________________________________________________________________________    Example 1                                                                           10.5                                                                              126    1037  0.82 538   9.2                                           Example 2 12.3 0.789 14.4 1.83 530 20.9                                       Comparative 10.5 20.5 98.0 0.48 550 7.5                                       Example 1                                                                   __________________________________________________________________________

Thus, the organic EL devices manufactured using the polymericfluorescent substance 1 of Example 1 or the polymeric fluorescentsubstance 2 of Example 2 had distinctly higher luminous efficienciesthan that of the organic EL device of Comparative Example 1 and showedexcellent EL properties.

EXAMPLE 3

[Synthesis of Polymeric Fluorescent Substance 4]

In a mixed solvent consisting of 100 parts by weight of ethyl alcoholand 100 parts by weight of chloroform were dissolved 1.95 parts byweight of 2,5-dioctyloxyterephthalaldehyde and 0.78 part by weight ofm-phenylene diacetonitrile. Thereto was added 0.3 part by weight of amethanol solution containing 28% by weight of sodium methoxide. Themixture was stirred at room temperature for 6 hours. Thereto was added200 parts by weight of ethyl alcohol. The mixture was allowed to standovernight at room temperature. The resulting precipitate was collectedby filtration, washed with ethyl alcohol, an ethyl alcohol/water mixedsolvent and again ethyl alcohol in this order, and dried under reducedpressure to obtain 0.5 part by weight of a polymer. This polymer isreferred to as polymeric fluorescent substance 4. The repeating units ofthe polymeric fluorescent substance 4 and the molar ratio thereof whichwas calculated from the ratio of the amounts of the monomers fed, isshown below. ##STR64##

The polymeric fluorescent substance 4 was an alternating copolymercomposed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 4 was 5×10³. The structure of the polymericfluorescent substance 4 was confirmed from the IR absorption spectrumand ¹ H-NMR.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 4 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 4 was high asseen from Table 8.

COMPARATIVE EXAMPLE 2

[Synthesis of Polymeric Fluorescent Substance 5]

In a mixed solvent consisting of 100 parts by weight of ethyl alcoholand 100 parts by weight of chloroform were dissolved 1.95 parts byweight of 2,5-dioctyloxyterephthalaldehyde and 0.78 part by weight ofp-phenylene diacetonitrile. Thereto was added 0.3 part by weight of amethanol solution containing 28% by weight of sodium methoxide. Themixture was stirred at room temperature for 6 hours. Thereto was added200 parts by weight of ethyl alcohol. The mixture was allowed to standovernight at room temperature. The resulting precipitate was collectedby filtration, washed with ethyl alcohol, an ethyl alcohol/water mixedsolvent and again ethyl alcohol in this order, and dried under reducedpressure to obtain 0.5 part by weight of a polymer. This polymer isreferred to as polymeric fluorescent substance 5. The repeating units ofthe polymeric fluorescent substance 5 and the molar ratio thereof whichwas calculated from the ratio of the amounts of the monomers fed, issown below. ##STR65##

The polymeric fluorescent substance 5 was an alternating copolymercomposed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 5 was 7×10³. The structure of the polymericfluorescent substance 5 was confirmed from the IR absorption spectrumand ¹ H-NMR.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 5 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 5 was low asseen from Table 8.

                  TABLE 8                                                         ______________________________________                                                   Peak wavelength                                                                         Quantum yield                                              of fluorescence fluorescence                                                  (nm) (arbitrary unit)                                                       ______________________________________                                        Example 3    570         13.8                                                   Comparative 640  3.3                                                          Example 2                                                                   ______________________________________                                    

Thus, the polymeric fluorescent substance 4 of Example 3 had a higherquantum yield of fluorescence in a thin film state than the polymericfluorescent substance 5 of Comparative Example 2 and showed excellentluminescence property.

EXAMPLE 4

[Synthesis of Polymeric Fluorescent Substance 6]

Synthesis, washing and reprecipitation were conducted in the same manneras in Example 1 except that 1.34 parts by weight of isophthalaldehydewas used as a dialdehyde compound, whereby a 3.02 parts by weight of apolymer was obtained. This polymer is referred to as polymericfluorescent substance 6. The repeating units of the polymericfluorescent substance 6 and the molar ratio thereof, which wascalculated from the ratio of the amounts of the monomers fed, are shownbelow. ##STR66## The polymeric fluorescent substance 6 was analternating copolymer composed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 15 6 was 7.3×10³. The measured elemental analysisvalues of the polymeric fluorescent substance 6 were 83.1% by weightcarbon, 9.4% by weight hydrogen, less than 0.3% by weight nitrogen andless than 0.2% by weight chlorine and almost agreed with the calculatedvalues. An NMR analysis confirmed that the observed hydrogen signalsalmost correspond to the structural formula obtained. Also, in the IRabsorption spectrum of the polymeric fluorescent substance 6, the intakeof isophthalaldehyde into said polymer was confirmed from the presenceof an absorption peak due to m-substituted benzene.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 6 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 6 was high asseen from Table 9.

EXAMPLE 5

[Synthesis of Polymeric Fluorescent Substance 7]

Synthesis, washing and reprecipitation were conducted in the same manneras in Example 1 except that there were used, as a phosphonium compound,8.50 parts by weight of a phosphonium compound obtained by reacting2,5-dioctyloxy-1,4-xylylene dibromide with triphenylphosphine inN,N-dimethylformamide, a solvent, and as a dialdehyde compound, 1.10parts by weight of pyridine-2,6-dialdehyde, whereby 0.50 part by weightof a polymer was obtained. The polymer is referred to as polymericfluorescent substance 7. The repeating units of the polymericfluorescent substance 7 and the molar ratio thereof, which wascalculated from the ratio of the amounts of the monomers fed, are shownbelow. ##STR67## The polymeric fluorescent substance 7 was analternating copolymer composed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 7 was 1.3×10⁴. The measured elemental analysisvalues of the polymeric fluorescent substance 7 were 80.3% by weightcarbon, 9.3% by weight hydrogen, 3.1% by weight nitrogen and less than0.2% by weight bromine and almost agreed with the calculated values. Thepresence of nitrogen atom confirmed the intake ofpyridine-2,6-dialdehyde into the polymer. An NMR analysis confirmed thatthe observed hydrogen signals almost correspond to the structuralformula obtained.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 7 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 7 was high asseen from Table 9.

COMPARATIVE EXAMPLE 3

[Synthesis of Polymeric Fluorescent Substance 8]

Synthesis, washing and reprecipitation were conducted in the same manneras in Example 1 except that there were used, as a phosphonium compound,7.67 parts by weight of a phosphonium compound obtained by reacting2,5-dimethoxy-1,4-xylylene dichloride with triphenylphosphine inN,N-dimethylformamide, a solvent, and as a dialdehyde compound, 1.34parts by weight of isophthalaldehyde, whereby 1.00 part by weight of apolymer was obtained. The polymer is referred to as polymericfluorescent substance 8. The repeating units of the polymericfluorescent substance 8 and the molar ratio thereof which was calculatedfrom the ratio of the amounts of the monomers fed, are shown below.##STR68## The polymeric fluorescent substance 8 was an alternatingcopolymer composed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 8 was 2.9×10³. The measured elemental analysisvalues of the polymeric fluorescent substance 8 were 78.4% by weightcarbon, 5.8% by weight hydrogen, less than 0.3% by weight nitrogen and1.9% by weight chlorine and almost agreed with the calculated values ofa polymer having terminals assumed from the relatively low molecularweight obtained. An NMR analysis confirmed that the observed hydrogensignals almost correspond to the structural formula obtained.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 8 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the thin film of the polymeric fluorescent substance 8 was low asseen from Table 9.

COMPARATIVE EXAMPLE 4

[Synthesis of Polymeric Fluorescent Substance 9]

Synthesis, washing and reprecipitation were conducted in the same manneras in Example 1 except that there were used, as a phosphonium compound,8.45 parts by weight of a phosphonium compound obtained by reacting2,5-diethyl-1,4-xylylene dibromide with triphenylphosphine inN,N-dimethylformamide, a solvent, and as a dialdehyde compound, 1.34parts by weight of isophthalaldehyde, whereby 1.00 part by weight of apolymer was obtained. The polymer is referred to as polymericfluorescent substance 9. The repeating units of the polymericfluorescent substance 9 and the molar ratio thereof which was calculatedfrom the ratio of the amounts of the monomers fed, are shown below.##STR69##

The polymeric fluorescent substance 9 was an alternating copolymercomposed of these two repeating units.

The polystyrene-reduced number-average molecular weight of the polymericfluorescent substance 9 was 4.8×10³. The measured elemental analysisvalues of the polymeric fluorescent substance 9 were 90.8% by weightcarbon, 7.4% by weight hydrogen, less than 0.3% by weight nitrogen and0.2% by weight bromine and almost agreed with the calculated values. AnNMR analysis confirmed that the observed hydrogen signals almostcorrespond to the structural formula obtained.

[Measurement of Absorption Spectrum and Fluorescence Spectrum andEvaluation of Quantum Yield of Fluorescence]

The polymeric fluorescent substance 9 was measured for fluorescenceintensity and peak wavelengths of absorption spectrum and fluorescencespectrum, in the same manner as in Example 1. The fluorescence intensityof the polymeric fluorescent substance 9 was low as seen from Table 9.

From the ratio of an absorption by benzene ring in the vicinity of 1,510cm⁻¹ and an absorption by m-substituted benzene in the vicinity of 690cm⁻¹ in the IR absorption spectrum, it was appreciated that the ratio ofisophthalaldehyde and terephthalaldehyde both taken into each of thepolymeric fluorescent substances 1, 2, 3 and 6 was almost identical tothe ratio of said aldehydes fed.

                  TABLE 9                                                         ______________________________________                                                   Peak wavelength                                                                         Quantum yield                                              of fluorescence of fluorescence                                               (nm) (arbitrary unit)                                                       ______________________________________                                        Example 1    538          9.2                                                   Example 2 530 20.9                                                            Example 4 504 42.7                                                            Example 5 572  8.1                                                            Comparative 550  7.5                                                          Example 1                                                                     Comparative 476  4.9                                                          Example 3                                                                     Comparative 450  1.9                                                          Example 4                                                                   ______________________________________                                    

Thus, the polymeric fluorescent substances 1, 2, 6 and 7 of Examples 1,2, 4 and 5, respectively, each had a higher quantum yield offluorescence in a thin film state than the polymeric fluorescentsubstance 3 of Comparative Example 1 having no m-substituted repeatingunit and the polymeric fluorescent substances 8 and 9 of ComparativeExamples 3 and 4, respectively, having only a substituent of 1-2 carbonatoms, and each showed excellent luminescence property.

What is claimed is:
 1. A polymeric fluorescent substance which issoluble in solvents, emits a fluorescence in a solid state, has apolystyrene-reduced number-average molecular weight of 10³ -10⁷ andcomprises a repeating unit of the following formula (9) and a repeatingunit of the following formula (10), respectively:

    --Ar.sub.10 --CR.sub.1 ═CR.sub.2 --                    (9)

    --Ar.sub.11 --CR.sub.3 ═--CR.sub.4 --                  (10)

wherein Ar₁₀ is a bifunctional group forming a carbon--carbon bond witheach of the adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-20 carbon atoms takingpart in the conjugated bonds and an at least 6-membered heterocyclicaromatic compound group having at least one hetero atom and 4-18 carbonatoms; in the chemical structure of Ar₁₀, the number of the consecutiveatoms present in the shortest path between the two carbon atoms bondingto said adjacent vinylene groups is 1 or 3; Ar₁₁ is a bifunctional groupforming a carbon--carbon bond with each of the adjacent vinylene groupsand is selected from the group consisting of an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 5-membered heterocyclic aromatic compound group having at leastone hetero atom and 4-18 carbon atoms; in the chemical structure ofAr₁₁, the total number of the carbon and/or nitrogen atoms present inthe shortest path between the two carbon atoms bonding to said adjacentvinylene groups is an even number; and R₁, R₂, R₃ and R₄ areindependently selected from the group consisting of a hydrogen atom, acyano group, an alkyl group of 1-20 carbon atoms and an aryl group of6-18 carbon atoms; and at least one of Ar₁₀ and Ar₁₁ includes at leastone of the group selected from the group consisting of an alkyl, alkoxylor alkylthio group of 4-20 carbon atoms, an aryl or aryloxy group of6-18 carbon atoms and a heterocyclic aromatic compound group of 4-14carbon atoms.
 2. A polymeric fluorescent substance according to claim 1,wherein the Ar₃ portion of formula (9) is selected from repeating unitseach containing at least one of the structures represented by thefollowing formula (5): ##STR70## wherein R₅ to R₃₇ are independently agroup selected from the group consisting of a hydrogen atom, a cyanogroup, an alkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, anaryl or aryloxy group of 6-18 carbon atoms and a heterocyclic compoundgroup of 4-14 carbon atoms.
 3. A polymeric fluorescent substanceaccording to claim 1 or 2, which is a copolymer comprising a repeatingunit represented by the following formula (11) and a repeating unitrepresented by the following formula (12) with the molar ratio of theformula (11) repeating unit and the formula (12) repeating unit being5:1 to 1:20: ##STR71## wherein X₃ is a group selected from the groupconsisting of and ═N--; and R₅₈ to R₆₁ are independently a groupselected from the group consisting of a hydrogen atom, an alkyl, alkoxylor alkylthio group of 1-20 carbon atoms, an aryl or aryloxy group of6-18 carbon atoms and a heterocyclic compound group of 4-14 carbonatoms, and ##STR72## wherein R₆₂ to R₆₅ are independently a groupselected from the group consisting of a hydrogen atom, an alkyl, alkoxylor alkylthio group of 1-20 carbon atoms, an aryl or aryloxy group of6-18 carbon atoms and a heterocyclic compound group of 4-14 carbonatoms; and at least one of R₆₂ to R₆₅ is a group selected from the groupconsisting of an alkyl, alkoxyl or alkylthio group of 4-20 carbon atoms,an aryl or aryloxy group of 6-18 carbon atoms and a heterocycliccompound group of 4-14 carbon atoms.
 4. A polymeric fluorescentsubstance according to claim 1 or 2, which is a copolymer furthercontaining, in addition to the formula (11) repeating unit and theformula (12) repeating unit, a repeating unit represented by thefollowing formula (13) with the molar ratio of the formula (11)repeating unit and the total of the repeating units of formulae (12) and(13) being 5:1 to 1:20 and the amount of the formula (12) repeating unitbeing at least 10 mole % based on the total repeating units: ##STR73##wherein R₆₆ to R₆₉ are independently a group selected from the groupconsisting of a hydrogen atom and an alkyl, alkoxyl or alkylthio groupof 1-3 carbon atoms.
 5. A polymeric fluorescent substance which issoluble in solvents, emits a fluorescence in a solid state, has apolystyrene-reduced number-average molecular weight of 10³ -10⁷ andcomprises a repeating unit represented by the following formula (14):##STR74## wherein Ar₁₂ is a bifunctional group forming a carbon--carboncarbon bond with each of two adjacent vinylene groups and is selectedfrom the group consisting of an aromatic compound group having 6-20carbon atoms taking part in the conjugated bonds and an at least5-membered hetero-cyclic compound group having at least one hetero atomand 4-18 carbon atoms; in the chemical structure of Ar₁₂, the totalnumber of the carbon and nitrogen atoms present in the shortest pathbetween the two carbon atoms bonding to said two adjacent vinylenegroups is an even number; Ar₁₃ is a bifunctional group forming acarbon--carbon bond with each of two adjacent vinylene groups and isselected from the group consisting of an aromatic compound group having6-20 carbon atoms taking part in the conjugated bonds and an at least6-membered heterocyclic compound group having at least one hetero atomand 4-18 carbon atoms; in the chemical structure of Ar₁₃, the number ofthe consecutive atoms present in the shortest path between the twocarbon atoms bonding to said two adjacent vinylene groups is 1, 3 or 5.6. A polymeric fluorescent substance which is soluble in solvents, emitsa fluorescence in a solid a state, has a polystyrene-reducednumber-average molecular weight of 10³ -10⁷ and comprises a repeatingunit represented by the following formula (15): ##STR75## wherein Ar₁₄is a bifunctional group forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered hetero-cyclic compound grouphaving at least one hetero atom and 4-18 carbon atoms; in the chemicalstructure of Ar₁₄, the total number of the consecutive atoms present inthe shortest path between the two carbon atoms bonding to said twoadjacent vinylene groups is 1, 3 or 5; Ar₁₅ is a bifunctional groupforming a carbon--carbon bond with each of two adjacent vinylene groupsand is selected from the group consisting of an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 5-membered heterocyclic compound group having at least one heteroatom and 4-18 carbon atoms; in the chemical structure of Ar₁₅, the totalnumber of the carbon and nitrogen atoms present in the shortest pathbetween the two carbon atoms bonding to said two adjacent vinylenegroups is an even number.
 7. A polymeric fluorescent substance which issoluble in solvents, emits a fluorescence in a solid state, has apolystyrene-reduced number-average molecular weight of 10³ -10⁷ and is acopolymer comprising a repeating unit represented by the followingformula (14) and a repeating unit represented by the following formula(16) with the total amount of the formula (14) repeating unit being atleast 5 mole % of the total repeating units: ##STR76## wherein Ar₁₂ is abifunctional group forming a carbon--carbon bond with each of theadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 5-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₂, the total number of the carbon and/ornitrogen atoms present in the shortest path between the two carbon atomsbonding to said adjacent vinylene groups is an even number; Ar₁₃ is abifunctional group forming a carbon--carbon bond with each of theadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₃, the number of the consecutive atomspresent in the shortest path between the two carbon atoms bonding tosaid adjacent vinylene groups is 1 or 3, and

    --Ar.sub.16 --CH═CH--                                  (16)

wherein Ar₁₆ is a bifunctional group forming a carbon--carbon bond witheach of the adjacent substituted or unsubstituted vinylene groups and isselected from the group consisting of an aromatic compound group having6-22 carbon atoms taking part in the conjugated bonds and an at least5-membered heterocyclic aromatic compound group having at least onehetero atom and 4-20 carbon atoms; in the chemical structure of Ar₁₆,the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said adjacentvinylene groups is an even number.
 8. A polymeric fluorescent substancewhich is soluble in solvents, emits a fluorescence in a solid state, hasa polystyrene-reduced number-average molecular weight of 10³ -10⁷ and isa copolymer comprising a repeating unit represented by the followingformula (15) and a repeating unit represented by the following formula(16) with the amount of the formula (15) repeating unit being at least 5mole % of the total repeating units: ##STR77## wherein Ar₁₄ is abifunctional group forming a carbon--carbon bond with each of theadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered heterocyclic aromaticcompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₄ the total number of the consecutive atomspresent in the shortest path between the two carbon atoms bonding tosaid adjacent vinylene groups is 1 or 3; Ar₁₅ is a bifunctional groupforming a carbon--carbon bond with each of the adjacent vinylene groupsand is selected from the group consisting of an aromatic compound grouphaving 6-20 carbon atoms taking part in the conjugated bonds and an atleast 5-membered heterocyclic aromatic compound group having at leastone hetero atom and 4-18 carbon atoms; in the chemical structure ofAr₁₅, the total number of the carbon and nitrogen atoms present in theshortest path between the two carbon atoms bonding to said adjacentvinylene groups is an even number, and

    --Ar.sub.16 --CH═CH--                                  (16)

wherein Ar₁₆ is a bifunctional group forming a carbon--carbon bond witheach of the adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-22 carbon atoms takingpart in the conjugated bonds and an at least 5-membered heterocyclicaromatic compound group having at least one hetero atom and 4-20 carbonatoms; in the chemical structure of Ar₁₆, the total number of the carbonand nitrogen atoms present in the shortest path between the two carbonatoms bonding to said adjacent vinylene groups is an even number.
 9. Apolymeric fluorescent substance which is soluble in solvents, emits afluorescence in a solid state, has a polystyrene-reduced number-averagemolecular weight of 10³ -10⁷ and comprises a repeating unit representedby the following formulae (14) or (15): ##STR78## wherein Ar₁₂ and Ar₁₅are bifunctional groups forming a carbon--carbon bond with each of twoadjacent vinylene groups and are selected from the group consisting ofan aromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 5-membered heterocyclic compound grouphaving at least one hetero atom and 4-18 carbon atoms; in the chemicalstructure of Ar₁₂, the total number of the carbon and/or nitrogen atomspresent in the shortest path between the two carbon atoms bonding tosaid two adjacent vinylene groups is an even number; Ar₁₃ and Ar₁₄ arebifunctional groups forming a carbon--carbon bond with each of twoadjacent vinylene groups and is selected from the group consisting of anaromatic compound group having 6-20 carbon atoms taking part in theconjugated bonds and an at least 6-membered heterocyclic compound grouphaving at least one hetero atom and 4-18 carbon atoms; in the chemicalstructure of Ar₁₃, the number of the consecutive atoms present in theshortest path between the two carbon atoms bonding to said two adjacentvinylene groups is 1, 3 or
 5. 10. A polymeric fluorescent substanceaccording to claim 9, wherein the Ar₁₃ portion of formula (14) ##STR79##or the Ar₁₄ portion of formula (15) ##STR80## is selected from repeatingunits each containing one of the structures represented by thefollowing: ##STR81## wherein R₅ to R₃₇ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms and a heterocyclic compound group of4-14 carbon atoms.
 11. A polymeric fluorescent substance according toclaim 9, wherein the Ar₁₂ portion of formula (14) ##STR82## or the Ar₁₅portion of formula (15) ##STR83## or the Ar₁₆ portion of formula (16)

    --Ar.sub.16 --CH═CH--                                  (16)

comprises a repeating unit represented by the following formula (17) andthe Ar₁₃ portion of formula (14) or the Ar₁₄ portion of formula (15)comprises a repeating unit represented by the following formula (18):##STR84## wherein X₂ is a group selected from the group consisting ofC--R₅₇ and N; and R₅₀ to R₅₇ are independently a group selected from thegroup consisting of a hydrogen atom, a cyano group, an alkyl, alkoxyl oralkylthio group of 1-20 carbon atoms, an aryl or aryloxy group of 6-18carbon atoms and a heterocyclic compound group of 4-14 carbon atoms. 12.A polymeric fluorescent substance which is soluble in solvents, emits afluorescence in a solid state, has a polystyrene-reduced number-averagemolecular weight of 10³ -10⁷ and is a copolymer comprising a repeatingunit selected from the repeating units represented by the followingformulae (14) or (15), and a repeating unit represented by the followingformula (16) with the total amount of the formula (14) repeating unitbeing at least 5 mole % of the total repeating units: ##STR85## whereinAr₁₂ and Ar₁₅ are bifunctional groups forming a carbon--carbon bond witheach of two adjacent vinylene groups and is selected from the groupconsisting of an aromatic compound group having 6-20 carbon atoms takingpart in the conjugated bonds and an at least 5-membered a heterocycliccompound group having at least one hetero atom and 4-18 carbon atoms; inthe chemical structure of Ar₁₂, the total number of the carbon and/ornitrogen atoms present in the shortest path between the two carbon atomsbonding to said two adjacent vinylene groups is an even number; Ar₁₃ andAr₁₄ are bifunctional groups forming a carbon--carbon bond with each oftwo adjacent vinylene groups and is selected from the group consistingof an aromatic compound group having 6-20 carbon atoms taking part inthe conjugated bonds and an at least 6-membered heterocyclic compoundgroup having at least one hetero atom and 4-18 carbon atoms; in thechemical structure of Ar₁₃, the number of the consecutive atoms presentin the shortest path between the two carbon atoms bonding to said twoadjacent vinylene groups is 1, 3 or 5, and

    --Ar.sub.16 --CH═CH--                                  (16)

wherein Ar₁₆ is a bifunctional group forming a carbon--carbon bond witheach of two adjacent substituted or unsubstituted vinylene groups and isselected from the group consisting of an aromatic compound group having6-22 carbon atoms taking part in the conjugated bonds and an at least5-membered heterocyclic compound group having at least one hetero atomand 4-20 carbon atoms; in the chemical structure of Ar₁₆, the totalnumber of the carbon and/or nitrogen atoms present in the shortest pathbetween the two carbon atoms bonding to said two adjacent vinylenegroups is an even number.
 13. A polymeric fluorescent substanceaccording to claim 2, wherein the Ar₁₃ portion of formula (14) or theAr₁₄ portion of formula (15) is selected from repeating units eachcontaining one of the structures represented by the following: ##STR86##wherein R₅ to R₃₇ are independently a group selected from the groupconsisting of a hydrogen atom, a cyano group, an alkyl, alkoxyl oralkylthio group of 1-20 carbon atoms, an aryl or aryloxy group of 6-18carbon atoms and a heterocyclic compound group of 4-14 carbon atoms. 14.A polymeric fluorescent substance according to claim 12, wherein theAr₁₂ portion of formula (14) or the Ar₁₅ portion of formula (15) or theAr₁₆ portion of formula (16) comprises a repeating unit represented bythe following formula (17) and the Ar₁₃ portion of formula (14) or theAr₁₄ portion of formula (15) comprises a repeating unit represented bythe following formula (18): ##STR87## wherein X₂ is a group selectedfrom the group consisting of C--R₅₇ and N; and R₅₀ to R₅₇ areindependently a group selected from the group consisting of a hydrogenatom, a cyano group, an alkyl, alkoxyl or alkylthio group of 1-20 carbonatoms, an aryl or aryloxy group of 6-18 carbon atoms and a heterocycliccompound group of 4-14 carbon atoms.
 15. A polymeric substance accordingto claim 9, wherein the Ar₁₂ portion of formula (14) or the Ar₁₅ portionof formula (15) comprises a repeating unit represented by the followingformula (17) and the Ar₁₃ portion of formula (14) or the Ar₁₄ Portion offormula (15) comprises a repeating unit represented by the followingformula (18): ##STR88## wherein X₂ is a group selected from the groupconsisting of C--R₅₇ and N; and R₅₀ to R₅₇ are independently a groupselected from the group consisting of a hydrogen atom, a cyano group, analkyl, alkoxyl or alkylthio group of 1-20 carbon atoms, an aryl oraryloxy group of 6-18 carbon atoms and a heterocyclic compound group of4-14 carbon atoms.
 16. A polymeric fluorescent substance according toclaim 12, wherein the Ar₁₆ portion of formula (16) comprises a repeatingunit represented by the following formula (17) and the Ar₁₃ portion offormula (14) or the Ar₁₄ portion of formula (15) comprises a repeatingunit represented by the following formula (18): ##STR89## wherein X₂ isa group selected from the group consisting of C--R₅₇ and N; and R₅₀ toR₅₇ are independently a group selected from the group consisting of ahydrogen atom, a cyano group, an alkyl, alkoxyl or alkylthio group of1-20 carbon atoms, an aryl or aryloxy group of 6-18 carbon atoms and aheterocyclic compound group of 4-14 carbon atoms.